An Interpretative Study on Circularly Polarized Patch Antenna Using Artificial Ground Structure

This communication presents some interpretative studies on a circularly polarized broadband patch antenna using an artificial ground structure (AGS). This patch antenna has a broadband characteristics in both impedance and axial ratio, which are more than 20% and 40%, respectively. The principle to expand the 3-dB axial ratio characteristics is discussed using a combination of circularly polarized patch antenna and an AGS polarizer. Furthermore, a broadband matching method using an extended outer conductor of coaxial cable is discussed. The mechanism of the matching structure is also discussed.